Amazon's Cashier-Less Seattle Grocery Opens To The Public : The Two-WayThe store, which has been open only to Amazon employees for the past year, uses a smartphone app and a network of cameras to track a customer's purchases.

"Every time customers grab an item off a shelf, Amazon says the product is automatically put into the shopping cart of their online account. If customers put the item back on the shelf, Amazon removes it from their virtual basket.

The only sign of the technology that makes this possible floats above the store shelves — arrays of small cameras, hundreds of them throughout the store."

The stores have no carts, either — just bring your own shopping bag.

Amazon has dubbed the technology "Just Walk Out" and, according to CNBC, "it uses computer vision, deep learning algorithms and sensor fusion — many of the same advances being used to develop autonomous driving."